Dynamic multi-antenna communication

ABSTRACT

According to exemplary embodiments described herein, communicating via a plurality of antennae includes transmitting different data streams from each of a first antenna and a second antenna in a first transmission mode, and transmitting identical data streams from a third antenna and one of the first and second antennae in a second transmission mode. The first and second antennae are horizontally stacked relative to each other and the third antenna is vertically stacked relative to both the first and second antennae.

This patent application is a continuation of U.S. patent applicationSer. No. 15/284,687, filed on Oct. 4, 2016, which is incorporated byreference in its entirety for all purposes.

TECHNICAL BACKGROUND

As wireless networks evolve and grow, there are ongoing challenges inproviding high-quality service to increasing numbers of wireless devicesin various coverage areas of a wireless network. Multiple-input andmultiple-output (MIMO) is used to multiply the capacity of a radiointerface using multiple transmit and receive antennas. Different typesof MIMO transmission modes may be used to communicate with the wirelessdevices attached to an access node. One such type of transmission modeutilizes transmit diversity, which includes sending redundant (i.e.identical) information across plural transmit antennas to improve thequality in the received signal. This transmission mode exploits thediversity of possible transmission paths between a transmitter and areceiver, thereby improving reliability and decreasing the probabilityof error. Another transmission mode uses spatial multiplexing, whichincludes transmitting an independent data stream on each antenna foreffectively sending multiple data streams in parallel. This mode enablestransmission of data generally at a higher rate, but typically lessreliably than with transmit diversity. Transmit diversity is well suitedfor wireless devices (and applications running thereon) requiringextremely high reliability such as at an edge of a coverage area,whereas wireless devices (and applications running thereon) that cansmoothly handle losses or are close to an access node benefit fromspatial multiplexing. However, existing access nodes are limited intheir ability to handle both transmission modes to their highestpotential, particularly when the arrangement and spacing of physicalantennae are not optimized.

Overview

Exemplary embodiments described herein include systems, methods, andprocessing nodes for communicating via a plurality of antennae. In oneexemplary embodiment, a method for communicating via a plurality ofantennae includes transmitting different data streams from each of afirst antenna and a second antenna in a first transmission mode, andtransmitting identical data streams from a third antenna and one of thefirst and second antennae in a second transmission mode. The first andsecond antennae are horizontally stacked relative to each other and thethird antenna is vertically stacked relative to both the first andsecond antennae.

In another exemplary embodiment, a system for communicating via aplurality of antennae includes a first antenna, a second antennapositioned horizontally adjacent the first antenna, a third antennapositioned vertically adjacent both the first and second antennae, and aprocessing node communicatively coupled to each of the first, second,and third antennae. The processing node is configured to determine atransmission mode from among a spatial multiplexing mode using the firstand second antennae and a transmit diversity mode using the thirdantenna and one of the first and second antennae.

In yet another exemplary embodiment, a processing node for communicatingvia a plurality of antennae is configured to perform operationscomprising utilizing a first pair of antennae in a spatial multiplexingtransmission mode, wherein the first pair of antennae ishorizontally-stacked and, upon a signal condition meeting a threshold,utilizing a second pair of antennae in a transmit diversity transmissionmode, wherein the second pair of antennae is vertically-stacked. Bothfirst and second pairs have one antenna in common.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary system for dynamic multi-antennacommunication.

FIGS. 2A-2B depict an exemplary access node for dynamic multi-antennacommunication and antennae thereof.

FIG. 3 depicts an exemplary method for dynamic multi-antennacommunication.

FIG. 4 depicts another exemplary method for dynamic multi-antennacommunication.

FIG. 5 depicts an exemplary processing node dynamic multi-antennacommunication.

DETAILED DESCRIPTION

In embodiments disclosed herein, a plurality of antennae of an accessnode can be configured in different pairs, enabling selection of eithera spatial multiplexing transmission mode or a transmit diversitytransmission mode. The access node may comprise at least three physicalantennae, i.e. a first antenna, a second antenna, and a third antenna.The at least three physical antennae are arranged such that a first pairof antennae, i.e. the first and second antennae, arehorizontally-stacked, and a second pair of antennae, i.e. the thirdantennae and one of the first and second antennae, arevertically-stacked. In other words, the first antenna is positionedhorizontally adjacent the second antenna, and the third antenna ispositioned vertically adjacent both the first and second antennae. Theantennae may be positioned such that a horizontal distance between thefirst and second antennae is less than or equal to half of an averagewavelength of signals transmitted by either of the first and secondantennae, thereby improving the gains provided by the spatialmultiplexing transmission mode. Additionally, the vertical separationbetween the third antennae and each of the first and second antennae issufficiently large to provide gains from the transmit diversitytransmission mode. Moreover, the at least three antennae may be enclosedwithin a single antenna pole, and at least one of the first, second, andthird antennae can further comprise a dual-band or tri-band antenna.

The configuration of each pair of antennae in each respectivetransmission mode may be performed by configuring thehorizontally-stacked pair (i.e. first and second antennae) to transmitdifferent data streams from each antenna, i.e. a spatial multiplexingtransmission mode. The vertically-stacked pair may be configured totransmit identical data streams from the third antenna and one of thefirst and second antennae, i.e. a transmit diversity transmission mode.The antenna pairs may be configured (and reconfigured) by mappinglogical antenna ports to each of the at least three physical antennae.For example, in the spatial multiplexing transmission mode, a firstantenna port is mapped to the first physical antenna in the first pair,and a second antenna port is mapped to the second physical antenna inthe first pair. Similarly, in the transmit diversity transmission mode,the first antenna port may continue to be mapped to the first physicalantenna, while the second antenna port may be remapped to the thirdphysical antenna, thereby forming the second pair of antenna comprisingthe first and third physical antennae. Other configurations of mappingports to physical antennae are possible, so long as the first and secondpairs are used to respectively communicate using the first and secondtransmission modes.

The access node (or any other network element) may be further configuredto determine the transmission mode from among the two transmission modesdescribed herein based on a signal condition. The signal condition maybe related to a sector served by one or more of the first, second, andthird antennae. For example, the signal condition may be obtained fromwireless devices accessing network services from the access node via oneor more of the three antennae. The signal condition can comprise asignal to interference plus noise ratio (SINR), or a number or rate ofhybrid automatic repeat request (HARQ) retransmissions, or any othermetric that provides an indication of coverage requirements of wirelessdevices at various locations around the network. For example, at certaintimes of the day, there may be an increased number of wireless devicesaround an edge of a coverage area, as determined by one or more signalconditions. It may be determined that a transmit diversity, i.e.identical data streams from different antennae in the pair, providesbetter coverage for these remote wireless devices. In another scenario,a dense cluster of wireless devices may be present in a small areanearby the access node (and antennae thereof). Spatial multiplexing,i.e. different data streams from different antennae in the pair, canprovide more efficient transmission in this scenario. The signalcondition (i.e. SINR or HARQ rate) can be compared with one or morethresholds in order to trigger a determination of which transmissionmode to implement. Further, the signal condition can be an average orother statistical determination based on a majority or all wirelessdevices, or individual measurements.

These and additional operations are further described with respect tothe embodiments depicted in FIGS. 1-5 below.

FIG. 1 depicts an exemplary system 100 for dynamic multi-antennacommunication. System 100 comprises a communication network 101, gateway102, controller node 104, access node 110, and end-user wireless devices121, 122, 123, 124. Access node 110 is illustrated as having coveragearea 111, and end-user wireless devices 121, 122, 123, 124 are locatedwithin coverage area 111 and access network services from access node110 via an air interface deployed by access node 110. The air interfacemay be deployed via a plurality of antennae coupled to access node 110,as further described in FIG. 2. Wireless device 121 is illustrated asbeing near a cell edge of coverage area 111, wireless devices 122comprise a dense cluster of wireless devices that are illustrated asbeing within a small geographical location within coverage area 111 andclose to access node 110, wireless device 123 is illustrated as beinglocated indoors, i.e. within a building that is well within coveragearea 111, and wireless device 124 is illustrated as being relativelyclose to access node 110.

In operation, access node 110 may monitor usage of its air interface,and determine which one out of two transmission modes to utilize. Thesignal condition may be related to a sector served by one or moreantennae coupled to access node 110, and may be reported to access node110 from one or more of wireless devices 121, 122, 123, 124. The signalcondition can comprise a signal to interference plus noise ratio (SINR),or a number or rate of hybrid automatic repeat request (HARQ)retransmissions, or any other metric that provides an indication ofcoverage requirements of wireless devices at various locations aroundthe network. For example, wireless device 121 at the edge of coveragearea 111, and wireless device 123 inside a building, may both sufferfrom reduced SINR and/or increase HARQ rates. In contrast, cluster ofwireless devices 122, and wireless device 124, may have sufficient SINRor low HARQ rates. Based on one or more signal conditions of each ofwireless devices 121-124, it may be determined that either a transmitdiversity transmission mode or a spatial multiplexing transmission modewould yield the best average conditions. For example, identical datastreams from different antennae (i.e., transmit diversity) providesbetter coverage for the remote/enclosed wireless devices 121, 123, whiledifferent data streams from different antennae (i.e., spatialmultiplexing) provides more efficient coverage for wireless devices 122,123. Since only one of the two transmission modes may be implemented atone time, an average signal condition (i.e. SINR or HARQ rate) can becompared with one or more thresholds in order to trigger a determinationof which transmission mode to implement. The determination may befurther based on a predictive signal condition based on, for instance,anticipated signal conditions upon implementing one or both transmissionmodes, or on actual signal conditions obtained subsequent toimplementing one or both transmission modes.

Upon determining a transmission mode, the antennae coupled to accessnode 110 may be configured (or reconfigured) in pairs, based on thedetermined transmission mode. For instance, in the spatial multiplexingtransmission mode, two antennae that are horizontally-stacked may beconfigured to transmit different data streams from each antenna. In thetransmit diversity transmission mode, two antennae that arevertically-stacked may be configured to transmit identical data streamseach antenna. The antenna pairs may be configured (and reconfigured) bymapping logical antenna ports to each of at least three antennae. Forexample, in the spatial multiplexing transmission mode, a first antennaport is mapped to the first physical antenna in the first pair, and asecond antenna port is mapped to the second physical antenna in thefirst pair. Similarly, in the transmit diversity transmission mode, thefirst antenna port may continue to be mapped to the first physicalantenna, while the second antenna port may be remapped to the thirdphysical antenna, thereby forming the second pair of antenna comprisingthe first and third physical antennae. Other configurations of mappingantenna ports to physical antennae are possible.

Access node 110 can be any network node configured to providecommunication between end-user wireless devices 121, 122, 123, 124 andcommunication network 101, including standard access nodes and/or shortrange, low power, small access nodes. For instance, access node 110 mayinclude any standard access node, such as a macrocell access node, basetransceiver station, a radio base station, an eNodeB device, an enhancedeNodeB device, or the like. In an exemplary embodiment, a macrocellaccess node can have a coverage area 111 in the range of approximatelyfive kilometers to thirty five kilometers and an output power in thetens of watts. In other embodiments, access node 110 can be a smallaccess node including a microcell access node, a picocell access node, afemtocell access node, or the like such as a home NodeB or a home eNodeBdevice. As further described herein and with reference to FIG. 2, accessnode 110 can operate using different frequencies or bands offrequencies, by virtue of having multi-band antennae. Moreover, it isnoted that while access node 110 is illustrated in FIG. 1, any number ofaccess nodes can be implemented within system 100.

Access node 110 can comprise a processor and associated circuitry toexecute or direct the execution of computer-readable instructions toperform operations such as those further described herein. Briefly,access node 110 can retrieve and execute software from storage, whichcan include a disk drive, a flash drive, memory circuitry, or some othermemory device, and which can be local or remotely accessible. Thesoftware comprises computer programs, firmware, or some other form ofmachine-readable instructions, and may include an operating system,utilities, drivers, network interfaces, applications, or some other typeof software, including combinations thereof. Further, access node 110can receive instructions and other input at a user interface. Accessnode 110 communicates with gateway node 102 and controller node 104 viacommunication links 106, 107. Access nodes 110 may communicate withother access nodes (not shown) using a direct link such as an X2 link orsimilar.

Wireless devices 121, 122, 123, 124 may be any device, system,combination of devices, or other such communication platform capable ofcommunicating wirelessly with access node 110 using one or morefrequency bands deployed therefrom. Each of wireless devices 121, 122,123, 124 may be, for example, a mobile phone, a wireless phone, awireless modem, a personal digital assistant (PDA), a voice overinternet protocol (VoIP) phone, a voice over packet (VOP) phone, or asoft phone, as well as other types of devices or systems that canexchange audio or data via access node 110. Other types of communicationplatforms are possible. One or more of wireless devices 121, 122, 123,124 may further comprise a relay node for relaying services from accessnode 110 to other end-user wireless devices. For example, wirelessdevice 123 may be a relay node for relaying network services to otherdevices within the building in which it is located.

Communication network 101 can be a wired and/or wireless communicationnetwork, and can comprise processing nodes, routers, gateways, andphysical and/or wireless data links for carrying data among variousnetwork elements, including combinations thereof, and can include alocal area network a wide area network, and an internetwork (includingthe Internet). Communication network 101 can be capable of carryingdata, for example, to support voice, push-to-talk, broadcast video, anddata communications by wireless devices 121, 122, 123, 124. Wirelessnetwork protocols can comprise MBMS, code division multiple access(CDMA) 1×RTT, Global System for Mobile communications (GSM), UniversalMobile Telecommunications System (UMTS), High-Speed Packet Access(HSPA), Evolution Data Optimized (EV-DO), EV-DO rev. A, Third GenerationPartnership Project Long Term Evolution (3GPP LTE), and WorldwideInteroperability for Microwave Access (WiMAX). Wired network protocolsthat may be utilized by communication network 101 comprise Ethernet,Fast Ethernet, Gigabit Ethernet, Local Talk (such as Carrier SenseMultiple Access with Collision Avoidance), Token Ring, Fiber DistributedData Interface (FDDI), and Asynchronous Transfer Mode (ATM).Communication network 101 can also comprise additional base stations,controller nodes, telephony switches, internet routers, networkgateways, computer systems, communication links, or some other type ofcommunication equipment, and combinations thereof.

Communication links 106, 107 can use various communication media, suchas air, space, metal, optical fiber, or some other signal propagationpath—including combinations thereof. Communication links 106, 107 can bewired or wireless and use various communication protocols such asInternet, Internet protocol (IP), local-area network (LAN), opticalnetworking, hybrid fiber coax (HFC), telephony, T1, or some othercommunication format—including combinations, improvements, or variationsthereof. Wireless communication links can be a radio frequency,microwave, infrared, or other similar signal, and can use a suitablecommunication protocol, for example, Global System for Mobiletelecommunications (GSM), Code Division Multiple Access (CDMA),Worldwide Interoperability for Microwave Access (WiMAX), or Long TermEvolution (LTE), or combinations thereof. Communications links 106, 107may include 51 communications links. Other wireless protocols can alsobe used. Communication links 106, 107 can be a direct link or mightinclude various equipment, intermediate components, systems, andnetworks. Communication links 106, 107 may comprise many differentsignals sharing the same link.

Gateway node 102 can be any network node configured to interface withother network nodes using various protocols. Gateway node 102 cancommunicate user data over system 100. Gateway node 102 can be astandalone computing device, computing system, or network component, andcan be accessible, for example, by a wired or wireless connection, orthrough an indirect connection such as through a computer network orcommunication network. For example, gateway node 102 can include aserving gateway (SGW) and/or a public data network gateway (PGW), etc.One of ordinary skill in the art would recognize that gateway node 102is not limited to any specific technology architecture, such as LongTerm Evolution (LTE) and can be used with any network architectureand/or protocol.

Gateway node 102 can comprise a processor and associated circuitry toexecute or direct the execution of computer-readable instructions toobtain information. Gateway node 102 can retrieve and execute softwarefrom storage, which can include a disk drive, a flash drive, memorycircuitry, or some other memory device, and which can be local orremotely accessible. The software comprises computer programs, firmware,or some other form of machine-readable instructions, and may include anoperating system, utilities, drivers, network interfaces, applications,or some other type of software, including combinations thereof. Gatewaynode 102 can receive instructions and other input at a user interface.

Controller node 104 can be any network node configured to communicateinformation and/or control information over system 100. Controller node104 can be configured to transmit control information associated with ahandover procedure. Controller node 104 can be a standalone computingdevice, computing system, or network component, and can be accessible,for example, by a wired or wireless connection, or through an indirectconnection such as through a computer network or communication network.For example, controller node 104 can include a mobility managemententity (MME), a Home Subscriber Server (HSS), a Policy Control andCharging Rules Function (PCRF), an authentication, authorization, andaccounting (AAA) node, a rights management server (RMS), a subscriberprovisioning server (SPS), a policy server, etc. One of ordinary skillin the art would recognize that controller node 104 is not limited toany specific technology architecture, such as Long Term Evolution (LTE)and can be used with any network architecture and/or protocol.

Controller node 104 can comprise a processor and associated circuitry toexecute or direct the execution of computer-readable instructions toobtain information. Controller node 104 can retrieve and executesoftware from storage, which can include a disk drive, a flash drive,memory circuitry, or some other memory device, and which can be local orremotely accessible. In an exemplary embodiment, controller node 104includes a database 105 for storing information such as historicaltrends of signal conditions and associations of signal conditions withwireless devices and transmission modes. This information may berequested by or shared with access node 110 via connections 106, 107, X2connections, and so on. The software comprises computer programs,firmware, or some other form of machine-readable instructions, and mayinclude an operating system, utilities, drivers, network interfaces,applications, or some other type of software, and combinations thereof.Controller node 107 can receive instructions and other input at a userinterface.

Other network elements may be present in system 100 to facilitatecommunication but are omitted for clarity, such as base stations, basestation controllers, mobile switching centers, dispatch applicationprocessors, and location registers such as a home location register orvisitor location register. Furthermore, other network elements that areomitted for clarity may be present to facilitate communication, such asadditional processing nodes, routers, gateways, and physical and/orwireless data links for carrying data among the various networkelements, e.g. between access node 110 and communication network 101.

FIGS. 2A-2B depict an exemplary access node for dynamic multi-antennacommunication and antennae thereof. With reference to FIG. 2A, accessnode 210 is configured as an access point for providing network servicesfrom network 201 to end-user wireless devices 222, 223 via antennae 231,232, 233. Access node 210 is illustrated as comprising a memory 212 forstoring logical modules that perform operations described herein, aprocessor 213 for executing the logical modules, and a transceiver 213for transmitting and receiving signals via antennae 231, 232, 233.Further, access node 210 is communicatively coupled to network 201 viacommunication interface 206, which may be any wired or wireless link asdescribed above. Although only one transceiver is depicted in accessnode 210, additional transceivers may be incorporated in order to deploymultiple frequency bands and to facilitate communication across othernetwork nodes that are not shown, such as gateways, controllers, andother access nodes.

In operations described herein, access node 210 may monitor usage of itsair interface deployed by one or more of antennae 231, 232, 233, anddetermine which one out of two transmission modes to utilize. The signalcondition may be reported to access node 210 from one or more ofwireless devices 222, 223, and can comprise an SINR, HARQ rate, or anyother metric of signal quality or strength. Wireless devices 222 mayhave sufficient SINR or low HARQ rates, and may benefit from a spatialmultiplexing transmission mode. Wireless device 223 may be enclosed in abuilding and have low SINR or high HARQ, and therefore benefit from atransmission diversity transmission mode. Based on one or more signalconditions (or averages thereof) meeting high or low thresholds asfurther described herein, a transmission mode may be determined, andantennae 231, 232, 233 may be configured as pairs, depending on thetransmission mode. For example, in a spatial multiplexing transmissionmode, antennae 231 and 232 (i.e., horizontally-stacked antenna pair 235)may be configured to transmit different data streams 236 from eachantenna in antenna pair 235. For example, in a transmit diversitytransmission mode, antennae 231 and 233 (i.e. vertically-stacked antennapair 237) may be configured to transmit identical data streams 238 fromeach antenna. The antenna pairs 235 and 237 may be configured (andreconfigured) by mapping logical antenna ports to each of antennae 231,232, 233. Further, although antenna pairs 235 and 237 are illustrated inFIG. 2A, any pairing may be used, such as a pairing of antennae 232 and233 for a transmit diversity transmission mode.

FIG. 2B depicts a detailed view of antennae 231, 232, 233. Each antenna231, 232, 233 may be a multi-band antenna. For example, each antennacomprises three sub-antennae for communicating with differentfrequencies or bands. For example, antenna 233 comprises sub-antennae233 _(a), 233 _(b), 233 _(c). Shaded antenna 233 _(b) may communicateusing, for instance, an 800 MHz frequency (or band of frequencies around800 MHz), while solid antennae 233 _(a), 233 _(c) may communicate using,for instance, a 2.5 GHz frequency (or band of frequencies around 2.5GHz). Further, the spacing of antennae 231, 232, and 233 is optimizedfor maximum gains from each transmission mode. For optimal spatialmultiplexing using horizontally-stacked antenna pair 231, 232, spacingx₁ and x₂ may be less than or equal to half of a wavelength used by eachsub-antenna of the antenna pair. For example, spacing x₁ may be lessthan half of a wavelength of the 2.5 GHz frequency band, and spacing x₂may be less than half of a wavelength of the 800 MHz frequency band.Further, distance y between antenna 233 and either antennae 231 or 232(i.e. a vertically-stacked antenna pair) is optimized for maximum gainsusing transmit diversity.

In some exemplary embodiments, sub-antennae 233 _(a), 233 _(b), 233 _(c)use the same band class across all three antennae 231, 232, 233.Alternatively or in addition, one sub-antenna of each antenna 231, 232,233 may use an 800 MHz frequency band while the other two may use a 2.5GHz frequency band. In such an embodiment, utilizing all threesub-antennae may be enabled by carrier aggregation and other techniques.Further, although only three sub-antennae 233 _(a), 233 _(b), 233 _(c)are depicted in FIG. 2B, each multi-band antennae 231, 232, 233 maycomprise any number of sub-antennae, with the possibility of variousconfigurations of band classes other than the ones described above.

FIG. 3 depicts an exemplary method for dynamic multi-antennacommunication. The method of FIG. 3 is illustrated with respect to anaccess node 110. In other embodiments, the method can be implementedwith any suitable network element. Although FIG. 3 depicts stepsperformed in a particular order for purposes of illustration anddiscussion, the operations discussed herein are not limited to anyparticular order or arrangement. One skilled in the art, using thedisclosures provided herein, will appreciate that various steps of themethods can be omitted, rearranged, combined, and/or adapted in variousways.

The method begins at 341, with a plurality of antennae of an access nodeconfigured to communicate in a spatial multiplexing mode. Since thespatial multiplexing (transmitting different data streams from eachantenna) is generally more efficient than transmit diversity mode(transmitting the same data stream from different antennae), it may beimplemented at 341 as a default transmission mode. Configuring antennaefurther comprises mapping antenna ports to physical antennae. Generally,the term “antenna port” refers to a logical entity versus a physicalantenna, and is used to describe signal transmission under identicalchannel conditions. For example, in an LTE operating mode in thedownlink direction for which an independent channel is assumed (e.g.SISO vs. MIMO), a separate logical antenna port is defined. LTE symbolsthat are transmitted via identical antenna ports are subject to the samechannel conditions. In order to determine the characteristic channel foran antenna port, a wireless device must carry out a separate channelestimation for each antenna port. Thus, separate reference signals thatare suitable for estimating the respective channel are defined in theLTE standard for each antenna port. See, for example, 3GPP TechnicalSpecification 36.211. In the present embodiment, a horizontally-stackedpair of physical antennae from among at least three physical antennae ofthe access node may be configured by mapping a first (logical) antennaport to a first physical antenna and a second antenna port to a secondphysical antenna, thereby forming a first pair of antennae comprisingthe first and second physical antennae.

At 342, a signal condition is monitored to enable subsequentdetermination 343 of which transmission mode to implement from among thetwo transmission modes. The signal condition may be related to a sectorserved by the antennae of the access node, and may be obtained fromwireless devices accessing network services from the access node via oneor more of the at least three antennae. The signal condition cancomprise a signal to interference plus noise ratio (SINR), or a numberor rate of hybrid automatic repeat request (HARQ) retransmissions, orany other metric that provides an indication of coverage requirements ofwireless devices at various locations around the network. The signalcondition can be an average or other statistical determination based ona majority or all wireless devices, or individual measurements. Further,at 343, the signal condition (i.e. SINR or HARQ rate) can be comparedwith one or more thresholds in order to trigger a determination ofwhether or not to switch transmission modes at 344. For example, if thetotal or average SINR drops to meet a low threshold, then it isdetermined that the wireless devices served by the at least threeantennae may receive better quality of service using a transmitdiversity transmission mode. In one exemplary embodiment, a lowthreshold for SINR is 0 db. Alternatively or in addition, if the totalor average HARQ rate or number of retransmissions rises above a highthreshold, this also represents a poor reception of wireless devices,and the transmit diversity transmission mode is implemented at 344. Inone exemplary embodiment, the high threshold for HARQ retransmissionrate is 15%. If neither threshold is met, then the method continuesmonitoring at 342.

If it is determined at 343 that a threshold is met, then thetransmission diversity transmission mode may be implemented at 344 byconfiguring a vertically-stacked pair of antennae to transmit identicaldata streams. For example, at least three physical antennae of theaccess node are arranged such that a first pair of antennae, i.e. firstand second antennae, are horizontally-stacked, and a second pair ofantennae, i.e. the third antennae and one of the first and secondantennae, are vertically-stacked. The vertically-stacked pair may beconfigured to transmit identical data streams from the third antenna andone of the first and second antennae, i.e. a transmit diversitytransmission mode. In one example, mapping antenna ports at 344 includesmaintaining the mapping of the first antenna port to the first physicalantenna, while the second antenna port may be remapped to the thirdphysical antenna, thereby forming the second pair of antenna comprisingthe first and third physical antennae. Alternatively, a new (third)antenna port is mapped to the third antenna, and the mapping of thesecond antenna port to the second antenna is removed, thus forming thesecond pair of antennae comprising the first and third physicalantennae. Other configurations of mapping ports to physical antennae arepossible, so long as the first and second pairs are used to respectivelycommunicate using the first and second transmission modes as describedherein.

FIG. 4 depicts another exemplary method for dynamic multi-antennacommunication. Similar to the method of FIG. 3, the method of FIG. 4 isillustrated with respect to an access node 110. In other embodiments,the method can be implemented with any suitable network element.Although FIG. 4 depicts steps performed in a particular order forpurposes of illustration and discussion, the operations discussed hereinare not limited to any particular order or arrangement. One skilled inthe art, using the disclosures provided herein, will appreciate thatvarious steps of the methods can be omitted, rearranged, combined,and/or adapted in various ways.

The method begins at 451, with a plurality of antennae of an access nodeconfigured to communicate in a transmit diversity transmission mode.Since transmit diversity mode (transmitting the same data stream fromdifferent antennae) is generally more reliable than the spatialmultiplexing (transmitting different data streams from each antenna), itmay be implemented at 451 as a default transmission mode. Configuringantennae further comprises mapping antenna ports to physical antennae,as described herein. For example, at least three physical antennae ofthe access node are arranged such that a first pair of antennae, i.e.first and second antennae, are horizontally-stacked, and a second pairof antennae, i.e. the third antennae and one of the first and secondantennae, are vertically-stacked. The vertically-stacked pair ofantennae are configured to transmit identical data streams from, forexample, the third antenna and one of the first and second antennae.Thus, mapping antenna ports at 451 includes mapping a first antenna portto a first physical antenna, and mapping a second antenna port to thethird physical antenna, thereby forming a first pair of antennacomprising the first and third physical antennae.

At 452, a signal condition is monitored to enable subsequentdetermination 453 of which transmission mode to implement from among thetwo transmission modes. The signal condition may be related to a sectorserved by the antennae of the access node, and may be obtained fromwireless devices accessing network services from the access node via oneor more of the at least three antennae. The signal condition cancomprise a signal to interference plus noise ratio (SINR), or a numberor rate of hybrid automatic repeat request (HARQ) retransmissions, orany other metric that provides an indication of coverage requirements ofwireless devices at various locations around the network. The signalcondition can be an average or other statistical determination based ona majority or all wireless devices, or individual measurements. Further,at 453, the signal condition (i.e. SINR or HARQ rate) can be comparedwith one or more thresholds in order to trigger a determination ofwhether or not to switch transmission modes at 454. For example, if thetotal or average SINR rises to meet a high threshold, then it isdetermined that a more efficient usage of resources may be achieved byusing a spatial multiplexing transmission mode. In one exemplaryembodiment, a high threshold for SINR is 0 db. Alternatively or inaddition, if the total or average HARQ rate or number of retransmissionsfalls to meet a low threshold, this also represents a satisfactoryquality of service for wireless devices, and the spatial multiplexingtransmission mode is implemented at 454. In one exemplary embodiment,the low threshold for HARQ retransmission rate is 15%. If neitherthreshold is met, then the method continues monitoring at 452.

If it is determined at 453 that a threshold is met, then the spatialmultiplexing transmission mode may be implemented at 454 by configuringthe horizontally-stacked pair of physical antennae (i.e. first andsecond antennae) to transmit different streams using spatialmultiplexing. In an exemplary embodiment, this includes maintaining themapping of the first antenna port to the first physical antenna, andmapping (or remapping) the second antenna port to the second physicalantenna, thereby forming a second pair of antennae comprising the firstand second physical antennae. Alternatively, a new (third) antenna portis mapped to the second antenna, and the mapping of the second antennaport to the third antenna is removed, thus forming the second pair ofantennae comprising the first and second physical antennae. Otherconfigurations of mapping ports to physical antennae are possible.

The methods, systems, devices, networks, access nodes, and equipmentdescribed above may be implemented with, contain, or be executed by oneor more computer systems and/or processing nodes. The methods describedabove may also be stored on a non-transitory computer readable medium.Many of the elements of communication system 100 may be, comprise, orinclude computers systems and/or processing nodes. This includes, but isnot limited to access nodes 110, 210, controller node 107, and/ornetwork 101.

FIG. 5 depicts an exemplary processing node 500 comprising communicationinterface 502, user interface 504, and processing system 506 incommunication with communication interface 502 and user interface 504.Processing system 506 includes storage 508, which can comprise a diskdrive, flash drive, memory circuitry, or other memory device. Storage508 can store software 510 which is used in the operation of theprocessing node 500. Storage 508 may include a disk drive, flash drive,data storage circuitry, or some other memory apparatus. For example,storage 508 may include a buffer. Software 510 may include computerprograms, firmware, or some other form of machine-readable instructions,including an operating system, utilities, drivers, network interfaces,applications, or some other type of software. For example, software 510may include a transmission mode determination module. Processing system506 may include a microprocessor and other circuitry to retrieve andexecute software 510 from storage 508. Processing node 500 may furtherinclude other components such as a power management unit, a controlinterface unit, etc., which are omitted for clarity. Communicationinterface 502 permits processing node 500 to communicate with othernetwork elements. User interface 504 permits the configuration andcontrol of the operation of processing node 500.

The exemplary systems and methods described herein can be performedunder the control of a processing system executing computer-readablecodes embodied on a computer-readable recording medium or communicationsignals transmitted through a transitory medium. The computer-readablerecording medium is any data storage device that can store data readableby a processing system, and includes both volatile and nonvolatilemedia, removable and non-removable media, and contemplates mediareadable by a database, a computer, and various other network devices.

Examples of the computer-readable recording medium include, but are notlimited to, read-only memory (ROM), random-access memory (RAM), erasableelectrically programmable ROM (EEPROM), flash memory or other memorytechnology, holographic media or other optical disc storage, magneticstorage including magnetic tape and magnetic disk, and solid statestorage devices. The computer-readable recording medium can also bedistributed over network-coupled computer systems so that thecomputer-readable code is stored and executed in a distributed fashion.The communication signals transmitted through a transitory medium mayinclude, for example, modulated signals transmitted through wired orwireless transmission paths.

The above description and associated figures teach the best mode of theinvention. The following claims specify the scope of the invention. Notethat some aspects of the best mode may not fall within the scope of theinvention as specified by the claims. Those skilled in the art willappreciate that the features described above can be combined in variousways to form multiple variations of the invention. As a result, theinvention is not limited to the specific embodiments described above,but only by the following claims and their equivalents.

What is claimed is:
 1. A method for communicating via a plurality ofantennae, the method comprising: determining, based on a signalcondition of a sector served by one or more of the plurality ofantennae, which transmission mode to utilize for a wireless transmissionto one or more wireless devices attached to an access node, wherein thetransmission mode is selected from a spatial multiplexing transmissionmode and a transmit diversity transmission mode; in the spatialmultiplexing mode, utilizing one or more horizontally stacked antennaefrom the plurality of antennae for the wireless transmission; and in thetransmit diversity mode, utilizing one or more vertically stackedantennae from the plurality of antennae for the wireless transmission;wherein at least one of the one or more horizontally stacked antennaecomprises a first plurality of sub-antennae and at least one of thevertically stacked antennae comprises a second plurality of sub-antennaethat is arranged vertically with respect to the first plurality ofsub-antennae.
 2. The method of claim 1, wherein using the spatialmultiplexing transmission mode comprises transmitting different datastreams from each of the one or more horizontally stacked antenna, andusing the transmit diversity transmission mode comprises transmittingidentical data streams from each of the vertically stacked antennae. 3.The method of claim 1, wherein the signal condition comprises an averagesignal to interference plus noise ratio (SINR).
 4. The method of claim3, further comprising determining that the average SINR is above athreshold, and using the spatial multiplexing transmission mode for thewireless transmission.
 5. The method of claim 1, wherein the signalcondition comprises an average rate of hybrid automatic repeat request(HARQ) retransmissions.
 6. The method of claim 5, further comprisingdetermining that the average rate of HARQ transmissions is below athreshold, and using the spatial multiplexing transmission mode.
 7. Amethod for communicating via a plurality of antennae, the methodcomprising: determining, based on a signal condition of a sector servedby one or more of the plurality of antennae, which transmission mode toutilize for a wireless transmission to one or more wireless devicesattached to an access node, wherein the transmission mode is selectedfrom a spatial multiplexing transmission mode and a transmit diversitytransmission mode; in the spatial multiplexing mode, utilizing a firstone or more sub-antennae from among the plurality of antennae that arehorizontally stacked; and in the transmit diversity mode, utilizing asecond one or more sub-antennae from among the plurality of antennaethat are vertically stacked; wherein the second one or more sub-antennaeare arranged vertically with respect to the first one or moresub-antennae.
 8. The method of claim 7, wherein using the spatialmultiplexing transmission mode comprises transmitting different datastreams from each of the first one or more sub-antennae, and using thetransmit diversity transmission mode comprises transmitting identicaldata streams from each of the second one or more antennae.
 9. The methodof claim 7, wherein the signal condition comprises an average signal tointerference plus noise ratio (SINR).
 10. The method of claim 9, furthercomprising determining that the average SINR is above a threshold, andusing the spatial multiplexing transmission mode for the wirelesstransmission.
 11. The method of claim 9, further comprising determiningthat the average rate of HARQ transmissions is below a threshold, andusing the spatial multiplexing transmission mode.
 12. The method ofclaim 7, wherein the signal condition comprises an average rate ofhybrid automatic repeat request (HARQ) retransmissions.
 13. The methodof claim 7, wherein a horizontal distance between each of the first oneor more sub-antennae is less than or equal to half of an averagewavelength of signals transmitted by the first one or more sub-antennae.14. The method of claim 13, wherein the horizontal distance is less thanor equal to half of a smallest wavelength transmitted by the first oneor more sub-antennae.
 15. A system for communicating via a plurality ofantennae, the system comprising: a first plurality of sub-antennae; asecond plurality of sub-antennae positioned horizontally adjacent thefirst plurality of sub-antennae; a third plurality of sub-antennaepositioned vertically adjacent both the first and second pluralities ofsub-antennae; and a processing node communicatively coupled to each ofthe first, second, and third pluralities of sub-antennae, the processingnode being configured to perform operations comprising: determining,based on a signal condition of a sector served by one or more of thefirst, second, and third pluralities of sub-antennae, a transmissionmode from among a spatial multiplexing transmission mode and a transmitdiversity transmission mode, in the spatial multiplexing transmissionmode, utilizing a first at least two sub-antennae from among the firstand second pluralities of sub-antennae, wherein the first at least twosub-antennae are horizontally arranged relative to each other; and inthe transmit diversity transmission mode, utilizing a second at leasttwo sub-antennae from among the first, second, and third pluralities ofsub-antennae, wherein the second at least two sub-antennae arevertically arranged relative to the first at least two sub-antennae. 16.The system of claim 15, wherein a spacing between each of the first atleast two sub-antennae is less than or equal to half of a wavelength ofsignals transmitted by the first at least two sub-antennae.
 17. Thesystem of claim 16, wherein the spacing is less than or equal to half ofa smallest wavelength of signals transmitted by the first at least twosub-antennae.
 18. The system of claim 15, wherein one or more of eachplurality of sub-antennae comprise dual-band antennae.
 19. The system ofclaim 15, wherein one or more of each plurality of sub-antennae comprisetri-band antennae.